EP3408031B1 - Bearing arrangement of a screw of a solid bowl screw centrifuge - Google Patents

Description

Background of the invention

The invention relates to a solid bowl screw centrifuge comprising a bearing arrangement of a screw with a centrifuge axis, a first axial bearing and a second axial bearing, in particular a bearing, which are provided for receiving an axial force of the screw.

Solid bowl screw centrifuges, also known as decanters, use a drum that rotates around a centrifuge axis at a drum speed to separate continuously flowable mixtures of substances into mostly a light and a heavy phase. The heavy phase is pushed inside the drum by a screw in a conveying direction to an end area of the drum. The screw is located in the drum and also rotates around the centrifuge axis. It rotates relative to the drum speed with a differential speed. When moving the heavy phase in the conveying direction, an axial force acts against the conveying direction. The axial force is taken up by a bearing arrangement of the worm. For this purpose, the bearing arrangement comprises at least one axial bearing. Solid bowl screw centrifuges are also known which have a first and a second axial bearing, both of which absorb the axial force of the screw in the axial direction. Such a device is from KR20120046900 known.

Such bearing arrangements with several axial bearings can indeed absorb higher overall axial forces than individual axial bearings, but it can still happen that individual axial bearings of these bearing arrangements become defective.

Underlying task

The invention is based on the object of creating a bearing arrangement in which several axial bearings are present, but which have a longer service life compared to known designs.

Solution according to the invention

This object is achieved according to the invention with a solid bowl screw centrifuge comprising a bearing arrangement of a screw, with a centrifuge axis, a first axial bearing and a second axial bearing, which are provided for absorbing an axial force of the screw, an elastic means being provided on which the second axial bearing for support the axial force of the worm is supported in the axial direction.

With conventional bearing arrangements for the screw of a solid bowl screw centrifuge with two axial bearings, it is difficult to calculate how the respective axial bearing is loaded with the axial force of the screw. According to the invention it was found that with such bearing arrangements it happens again and again that individual axial bearings are loaded beyond their load limit.

In the bearing arrangement according to the invention, on the other hand, an elastic means is provided on which the second axial bearing is supported in the axial direction to support the axial force of the worm. An elastic means has the property that it changes its shape under the action of a force and when this force decreases it deforms back in the direction of its original shape. In relation to the action of force, an elastic means has an elasticity with a spring constant must be specified. According to the invention, the second axial bearing is supported on such an elastic means in such a way, the elastic means then being correspondingly compressed as the axial force of the worm increases. The elastic medium is reduced in size with the compression and the screw moves in the axial direction. With the movement of the worm in the axial direction, an increasing axial force is then exerted on the first axial bearing. At the same time, the elastic means according to the invention ensure that the second axial bearing cannot be overloaded.

In order, in particular, to load both axial bearings equally with the axial force, the spring constant of the elastic means is advantageously selected according to the invention so that the maximum axial force that occurs is equally distributed over both axial bearings. In this way, overloading the first axial bearing must also be avoided. In addition to this advantage, the elastic means can also cushion shocks and vibrations of the screw in certain construction situations and it can compensate for changes in the shape of components, such as, for example, a thermal change in length or abrasion due to wear.

The force distribution according to the invention has the effect that the axial force is distributed and limited in an exactly predetermined manner on each axial bearing. The individual load on the respective axial bearing is thus a maximum of only half of the maximum axial force. The respective axial bearing can thus be dimensioned particularly small. With such small axial bearings, the radial overall height of the bearing arrangement is also particularly low. This low radial overall height of the bearing arrangement is particularly advantageous when working with a large pond depth in the solid bowl screw centrifuge. This means that the material located in the solid bowl screw centrifuge protrudes radially inward and accordingly only little space remains for the hub of the screw there and its bearing arrangement in the radial direction.

The elastic means is advantageously arranged between the first and the second axial bearing. With this arrangement of the elastic means, it is located directly between the two axial bearings and uses an installation space available there. At the same time, with a load and displacement of the second axial bearing, the elastic means is immediately compressed. This arrangement has otherwise only a low residual elasticity. An increasing axial force of the worm thus leads directly to a compression of the elastic means and an associated, correspondingly direct transfer of the axial force to the first axial bearing.

Furthermore, the first and the second axial bearing are each advantageously designed with an inner bearing ring and an outer bearing ring. The elastic means is arranged between the two bearing inner rings and a less elastic, in particular a non-elastic means is arranged between the two bearing outer rings. The bearing inner ring is the radially inner ring with respect to its axis of rotation, which is the centrifuge axis in the present case. The bearing outer ring is accordingly the ring located radially on the outside. The elastic means is then arranged between the two end faces of the bearing inner rings which face one another in the axial direction. The less elastic or non-elastic means is arranged between the two end faces of the bearing outer rings facing each other in the axial direction. The elastic means is compressed more strongly than the less elastic or the non-elastic means when one and the same force is applied. As a result, when the axial force of the worm acts on such a bearing arrangement, the bearing outer rings of both axial bearings are displaced. At the same time, the inner bearing ring of one axial bearing is displaced relative to the inner bearing ring of the other axial bearing. This changes the spatial situations between the bearing outer rings and the associated bearing inner rings and thus the load situations of the axial bearings.

Alternatively, the first and the second axial bearing are advantageously each designed with an inner bearing ring and an outer bearing ring, and at the same time the one is elastic Means are arranged between the two bearing outer rings and a less elastic, in particular a non-elastic means is arranged between the two bearing inner rings. This embodiment is functionally reversed to the embodiment explained last above. Correspondingly, in this embodiment it is possible to work with somewhat differently designed axial bearings, which can be particularly advantageous in certain installation space situations.

Furthermore, the second axial bearing is preferably designed as a spindle bearing and the first axial bearing as a deep groove ball bearing. A spindle bearing and a deep groove ball bearing are axial bearings in different designs. Both designs have, in particular, spherical rolling elements that each run on a raceway between an inner bearing ring and an outer bearing ring. The raceway has a pressure angle or contact angle relative to the radial direction of the axial bearing. The contact angle of the raceways of deep groove ball bearings is usually 0 ° (in words: zero degrees). In the case of spindle bearings, the pressure angle is usually between 10 and 30 ° (in words: ten and thirty degrees), particularly advantageously between 20 and 30 ° (in words: twenty and thirty degrees). The larger the pressure angle, the more axial force the spindle bearing can absorb. Since the pressure angle of the spindle bearing is adapted to the resulting axial force, the bearing arrangement according to the invention is particularly easy to dimension. The deep groove ball bearing particularly absorbs forces in the radial direction. Such a radial ball bearing actually only absorbs small forces in the axial direction. According to the invention, however, it can be used particularly advantageously because it is ensured that it is not overloaded in the axial direction. This also makes use of the advantage that radial ball bearings are inexpensive, low-maintenance and easily available.

Alternatively, the second axial bearing is also designed as an angular contact ball bearing and the first axial bearing is designed as a deep groove ball bearing. An angular contact ball bearing usually has a contact angle between 15 and 60 ° (in words: fifteen and sixty degrees), particularly preferably between 40 and 50 ° (in words: forty and fifty degrees). In this type of bearing, too, the contact angle influences the capacity to absorb axial force. An angular contact ball bearing can absorb more axial force than a spindle ball bearing due to the larger pressure angle. An angular contact ball bearing is accordingly advantageous in the case of a greater axial force.

The second axial bearing is preferably designed as an angular contact ball bearing and the first axial bearing is designed as a four-point bearing. In particular, a four-point bearing has a pressure angle of around 35 ° (in words: thirty-five degrees). In the case of a four-point bearing, the rolling elements there have four contact points on the respective raceways. Four point bearings also advantageously have a split bearing inner ring or a split bearing outer ring. Due to bearing rings divided in this way, more rolling elements can be installed in a four-point bearing than in an angular contact ball bearing of the same size. Due to the larger number of rolling elements and the four contact points, four-point bearings can absorb both a comparatively large axial force and a large radial force. In addition, four-point bearings are easy to assemble due to the split bearing rings.

Furthermore, the second axial bearing is advantageously designed as a tapered roller bearing and the first axial bearing as a deep groove ball bearing. In the case of tapered roller bearings, in contrast to the aforementioned bearings, the rolling elements are not spherical, but rather conical. The rolling element of the tapered roller bearing does not run on a raceway, but on a comparatively wide running surface. Tapered roller bearings can absorb a very high axial force and a very high radial force. In addition, tapered roller bearings are particularly easy to assemble because their bearing outer ring is initially loose and can be assembled separately.

Furthermore, a third axial bearing is particularly preferably provided for absorbing an axial force of the worm, and a further elastic means is provided on which the third axial bearing is supported in the axial direction. In this arrangement, the third axial bearing is connected in series in addition to the other two axial bearings. The third axial bearing has the effect that the axial force is divided between these three axial bearings. The individual load on the respective axial bearing is thus preferably only one third the maximum axial force. The respective axial bearing can thus be made particularly small.

According to the invention, the elastic means, in particular the further elastic means, is particularly preferably pretensioned. The pre-tensioning results in particular from the fact that the elastic means is already pre-compressed in the built-in rest state. Such pre-compression of the elastic means with a pretensioning force has the effect that a force is exerted by it on the adjacent components even in the state of rest. The biasing force of the elastic means is preferably in the range of 2,500 to 300,000 Newtons (in words two thousand five hundred to three hundred thousand Newtons). Especially with small solid bowl screw centrifuges in the range from 2,500 to 10,000 Newtons (in words: two thousand five hundred to ten thousand Newtons). In the case of medium-sized solid bowl screw centrifuges in the range from 10,000 to 100,000 (in words: ten thousand to one hundred thousand Newtons), in particular 30,000 Newtons (in words: thirty thousand Newtons) and in the case of large solid bowl screw centrifuges in the range from 100,000 to 300,000 Newtons (in words: one hundred thousand to three hundred thousand Newtons). In the case of two axial bearings, the preload force preferably corresponds to half of the maximum axial force in the operating state. The preload force has the effect, in particular, that both bearings are loaded with opposing axial forces in the idle state. If the axial force of the worm in the operating state is less than the preload force, the second axial bearing is additionally loaded with axial force and the first axial bearing is relieved. If the axial force that occurs is equal to the preload force, there is no longer any axial force acting on the first axial bearing. With an axial force greater than the preload force, an axial force acts on both axial bearings in only one direction. Surprisingly, it has emerged that with such a preload the associated axial bearings are loaded particularly evenly and the maintenance intervals and replacement intervals of the axial bearings can be determined particularly easily.

Brief description of the drawings

Fig. 1

einen Längsschnitt einer Vollmantelschneckenzentrifuge gemäß dem Stand der Technik entlang deren Zentrifugenachse,

Fig. 2

das Detail II gemäß Fig. 1 ,

Fig. 3

einen Längsschnitt einer Vollmantelschneckenzentrifuge gemäß eines ersten Ausführungsbeispiels der Erfindung,

Fig. 4

das Detail IV gemäß Fig. 3,

Fig. 5

das Detail V gemäß Fig. 4 einer ersten Variante,

Fig. 6

das Detail VI gemäß Fig. 4 einer zweiten Variante,

Fig. 7

das Detail VII gemäß Fig. 4 einer dritten Variante,

Fig. 8

das Detail VIII gemäß Fig. 4 einer vierten Variante,

Fig. 9

das Detail IX gemäß Fig. 4 einer fünften Variante,

Fig. 10

das Detail X gemäß Fig. 4 einer sechsten Variante und

Fig. 11

das Detail XI gemäß Fig. 4 einer siebten Variante.

An exemplary embodiment of the solution according to the invention is explained in more detail below with reference to the accompanying schematic drawings. It shows:

Fig. 1

a longitudinal section of a solid bowl screw centrifuge according to the prior art along its centrifuge axis,

Fig. 2

the detail II according to Fig. 1 ,

Fig. 3

a longitudinal section of a solid bowl screw centrifuge according to a first embodiment of the invention,

Fig. 4

the detail IV according to Fig. 3 ,

Fig. 5

the detail V according to Fig. 4 a first variant,

Fig. 6

the detail VI according to Fig. 4 a second variant,

Fig. 7

the detail VII according to Fig. 4 a third variant,

Fig. 8

the detail VIII according to Fig. 4 a fourth variant,

Fig. 9

the detail IX according to Fig. 4 a fifth variant,

Fig. 10

the detail X according to Fig. 4 a sixth variant and

Fig. 11

the detail XI according to Fig. 4 a seventh variant.

Detailed description of the embodiment

Fig. 1 shows a solid bowl screw centrifuge 10 with its hollow cylindrical centrifuge drum 14 rotatable about a centrifuge axis 12. The centrifuge axis 12 defines an axial direction 16 and a radial direction 18. The centrifuge drum 14 is surrounded by a housing 20 and at its two axial end regions by means of a first drum bearing 22 and a second drum bearing 24 stored. The first drum bearing 22 supports the centrifuge drum 14 on a drum cover 26. The drum cover 26 in turn supports a screw 32 in the centrifuge drum 14 by means of a bearing arrangement 28. The bearing arrangement 28 is designed with a thrust bearing 30.

The worm 32 comprises an essentially hollow cylindrical worm hub 34 and a worm helix 36 surrounding it radially on the outside. The worm hub 34 is rotatably supported at its one axial end area by means of the bearing arrangement 28 and at its other axial end area by means of a worm bearing 38 within the centrifuge drum 14.

An inlet pipe 40 leads into the centrifuge drum 14 through the drum bearing 22 and the first drum cover 26. The inlet pipe 40 extends along the centrifuge axis 12 to an inlet space 42 within the screw hub 34. The inlet pipe 40 serves to supply mixed material 44, present sewage sludge. The mixed material 44 flows radially outward from the inlet space 42 into a separation space 46. In the separation space 46, the mixed material 44 is separated or separated into a heavy phase 48, in this case dewatered sewage sludge, and in a light phase 50, in this case clarified liquid. clarified. The heavy phase 48 flows outward in the radial direction 18 due to the centrifugal force that occurs and rests against the inside of the centrifuge drum 14. The light phase 50 floats radially inward on the heavy phase 48.

Both phases 48 and 50 together result in a liquid level 51 in the separation space 46. The distance between the liquid level 51 and the inside of the centrifuge drum 14 is usually referred to as the pond depth 52. The pond depth 52 is determined by outlet openings 54, at each of which a weir plate 56 is provided for the defined retention of the light phase 50. The outlet openings 54 are formed in the drum cover 26 around the centrifuge axis 12. The weir plates 56 are overflowed by the emerging light phase 50. Their radial position thus defines the pond depth 52.

Ejection openings 58 for the heavy phase 48 are located on the outside in the radial direction at the end region of the centrifuge drum 14 opposite the first drum cover 26. For this purpose, the heavy phase 48 is opened by means of the helical screw 36 moved radially inward in a conveying direction 60 towards the ejection openings 58. The heavy phase 48 is then thrown out of the centrifuge drum 14 through the ejection openings 58 due to the centrifugal force of the rotating centrifuge drum 14. Against the conveying direction 60, an axial force 62 occurs on the screw helix 36, which at the same time pushes the entire screw 32 in the direction of the drum cover 26.

At the center of the drum cover 26 around the inlet pipe 40 there is a tubular, inwardly protruding support area 64 which is connected in one piece to the drum cover 26. The support area 64 carries or supports the bearing arrangement 28 at its end area directed into the interior of the centrifuge drum 14.

The radial height of the support area 64, a bearing height 66 of the bearing arrangement 28 and a wall thickness 68 of the screw hub 34 on the bearing arrangement 28 together define an outer diameter 70 of the screw hub 34. The outer diameter 70 of the screw hub 34 and an inner diameter 72 of the centrifuge drum 14 also determine the maximum Pond depth 52 of the solid bowl centrifuge 10.

Fig. 2 illustrates a bearing arrangement 28 according to the prior art with only a single axial bearing 30. The axial bearing 30 comprises an inner bearing ring 74 in the radial direction 18, which is pressed onto the support area 64 of the drum cover 26. At the axially inner end of the support area 64 there is a fixing ring 76 with an L-shaped cross section, which axially fixes the bearing inner ring 74 on the support area 64. The bearing inner ring 74 has a bearing track 78 on the outside in the radial direction 18, along which at least one spherical roller body 80 rolls in the circumferential direction around the bearing inner ring 74. On the rolling element 80, diametrically opposite the bearing track 78, there is an outer bearing track 78 on a bearing outer ring 82. The bearing outer ring 82 is pressed into the worm hub 34 and is axially supported on it. The bearing outer ring 82 is further axially fixed at the axial end of the worm hub 34 by means of a fixing ring 84 with an L-shaped cross section. The worm hub 34 also has a greater wall thickness 68 at its axial end region in the radial direction 18 than at its remaining longitudinal extent. The greater wall thickness 68 is required to support the bearing outer ring 82.

In the axial direction 16 to the left and right of the bearing arrangement 28, an annular seal 86, 88 is arranged on each fixing ring 76, 84, which seals the bearing arrangement 28 on both axial sides.

Fig. 3 shows a solid bowl screw centrifuge 10 with a first embodiment of a bearing arrangement 28 according to the invention, which is shown in detail IV in FIG Fig. 4 is shown. The solid bowl screw centrifuge 10 according to Figures 3 and 4 also comprises a centrifuge drum 14 and a screw 32, the bearing height 66 of the bearing arrangement 28 according to the invention being shown here as well. This bearing height 66 is less than in the case of the bearing arrangement 28 according to FIG Fig. 1 . Since the bearing height 66 is smaller, the outer diameter 70 of the associated worm hub 34 is also smaller. In addition, in the case of the bearing arrangement 28 according to the invention, the wall thickness 68 of the worm hub 34 is less. The smaller wall thickness 68, in addition to the smaller bearing height 66, reduces the outer diameter 70 of the worm hub 34.

With a reduced outer diameter 70 of the screw hub 34 and the same inner diameter 72 of the centrifuge drum 14, the distance between the two is increased and the volume of the separating space 46 increases. With a greater distance between the centrifuge drum 14 and the screw hub 34, the pond depth 52 of the solid-bowl screw centrifuge 10 also increases in this way. The solid-bowl screw centrifuge 10 according to FIG Figures 3 and 4 can take up and separate more material 44 in its separation space 46.

The bearing arrangement 28 comprises according to Fig. 4 A first and a second axial bearing 90, 92 next to one another in the axial direction 16. Both axial bearings 90, 92 each have a bearing inner ring 94 and 96, respectively. The two bearing inner rings 94, 96 are supported by the support area 64 of the drum cover 26. The inner bearing ring 94 of the first axial bearing 90 is pressed in a stationary manner onto the support area 64. In this way, the first axial bearing 90 is designed as a fixed bearing. In the case of the second inner bearing ring 96, the support area 64 is reduced in size in the radial direction 18 towards the centrifuge axis 12, so that the second inner bearing ring 96 is loose or movable. In this way, the second axial bearing 92 is designed as a floating bearing. Both bearing inner rings 94, 96 are also retained towards the inner end of the support area 64 by means of the fixing ring 84 in the axial direction 16.

An annular, elastic means 98 is arranged between the two inner bearing rings 94, 96 in the axial direction 16. The elastic means 98 comprises two plate springs 100, 102 lined up in a row. The form of the arrangement of the two plate springs 100, 102 in a row is also referred to as a series connection. The first disk spring 100 is supported on the bearing inner ring 94 and the second disk spring 102 is supported on the bearing inner ring 96.

When the bearing arrangement 28 of this type is loaded by the worm 32 with axial force 62 in the direction of the drum cover 26, this axial force first acts on the axial bearing 92 and loads it. As a result, the loose bearing inner ring 96 is displaced by the axial force 62 towards the stationary bearing inner ring 94. The inner bearing ring 96 presses on the plate spring 102, which transfers the force to the first plate spring 100. The first plate spring 100 in turn transmits the force to the first bearing inner ring 94. In this way, the two disc springs 100, 102 oppose the axial force 62 with a force which acts on the axial bearing 92, while at the same time the remainder of the axial force 62 acts on the axial bearing 90. The axial force 62 is therefore evenly distributed to both bearing inner rings 94, 96 and thus to both axial bearings 90 and 92, respectively.

Furthermore, both bearing inner rings 94, 96 each have a bearing track 78 outward in the axial direction 16, on which spherical rolling elements 80 roll. In the case of the rolling elements 80, diametrically opposite one another, the bearing track 78 is formed in a first and second bearing outer ring 104, 106. The two bearing outer rings 104, 106 support the worm hub 34 in the axial direction 16 and radial direction 18. Both bearing outer rings 104, 106 are pressed into the worm hub 34 and held by the first fixing ring 76.

According to the invention, an annular, less elastic means 108, in particular a non-elastic means 110, is arranged between the two bearing outer rings 104, 106 in the axial direction 16. The less elastic means 108, in the present case made of rubber-like material, gives the axial force 62 from the worm 32 to the second bearing outer ring 104. The second bearing outer ring 106 gives the axial force 62 to the less elastic means 108, which in turn dampens the axial force 62 on the first bearing outer ring 104 passes. The first and second bearing outer rings 104 and 106 emit the axial force 62 via their respective bearing tracks 78 to the respective rolling elements 80. The rolling elements 80 in turn transmit the force to the respective bearing inner rings 94 and 96 via the respective bearing tracks 78. The first and second bearing outer rings 104, 106 shift in the axial direction 16 against the first and second bearing inner rings 94, 96.

Fig. 5 shows the bearing arrangement 28 in which the first axial bearing 90 is designed as a movable floating bearing and the second axial bearing 92 is designed as a fixed bearing. For this purpose, in the first axial bearing 90, a groove 112 is formed in the area of the worm hub 34. The groove 112 has the effect that the first bearing outer ring 104 of the first axial bearing 90 can be moved in the axial direction 16. In contrast, the first bearing inner ring 94 of the first axial bearing 90 is pressed onto the support area 64.

The second axial bearing 92 is pressed with its second bearing inner ring 96 into the worm hub 34 and held in a supporting manner by the worm hub 34. The second inner bearing ring 96 is pressed onto the support area 64.

In this first variant of the bearing arrangement 28, the elastic means 98 and the less elastic means 108, in particular the non-elastic means 110, are interchanged. The elastic means 98 is between the first and second bearing outer rings 104, 106 and the less elastic means 108 is designed here as a non-elastic means 110 and is arranged between the first and second bearing inner rings 94, 96.

In Fig. 6 the bearing arrangement 28 is shown in which both axial bearings 90 and 92 as in FIG Fig. 4 are arranged, so the first axial bearing 90 is a fixed bearing and the second axial bearing 92 is a floating bearing. In the second variant of the bearing arrangement 28, the first axial bearing 90 is designed as a deep groove ball bearing 114 and the second axial bearing 92 is designed as a spindle bearing 116. The deep groove ball bearing 114 and the spindle bearing 116 are axial bearings in a different design with spherical rolling elements 80. The rolling elements 80 run in the circumferential direction on the respective bearing inner rings 94, 96 and the respective bearing outer rings 104, 106 each on bearing tracks 78. The bearing tracks 78 each form a career 118 from. The raceway 118 has a pressure angle 120 or contact angle relative to the radial direction 18 of the respective axial bearing 90, 92. The pressure angle 120 of the raceway 118 of the deep groove ball bearing 114 is 0 degrees here (in words: zero degrees). Because of the small pressure angle 120, it is not shown. The pressure angle 120 in the raceway 118 in the spindle bearing 116 is here 25 ° (in words: twenty-five degrees).

Fig. 7 shows the bearing arrangement 28 in which the first axial bearing 90 is designed as a deep groove ball bearing 114 and the second axial bearing 92 is designed as an angular contact ball bearing 122. The angular contact ball bearing 122 is a special form of the spindle bearing 116 Fig. 6 with a pressure angle of 120 between 20 ° and 50 ° (in words: twenty degrees and fifty degrees). The contact angle 120 in the angular contact ball bearing 122 is 45 ° here (in words: forty-five degrees).

Fig. 8 shows the bearing arrangement 28 with the second axial bearing 92 as an angular contact ball bearing 122 and the first axial bearing 90 as a four-point bearing 124. The four-point bearing 124 is a special form of the angular contact ball bearing 122 from Fig. 7 . In the four-point bearing 124, in contrast to the angular contact ball bearing 122, there are four contact points 126 of the rolling elements 80. The contact points 126 of the rolling elements 80 form four bearing tracks 78 in the circumferential direction. Two of the bearing tracks 78 are formed on the first bearing outer ring 104 and two of the bearing tracks 78 are formed on the first bearing inner ring 94. In the four-point bearing 124, the inner bearing ring 94 is divided into a first and a second annular half 128, 130. The first and second halves 128, 130 each include a bearing track 78 of the bearing inner ring 94. The bearing tracks 78, which are each diametrically opposite on the rolling element 80, each form a track 118. The two raceways 118 in a four-point bearing 124 have a pressure angle 120 of around 35 ° (in words: thirty-five degrees). In Fig. 8 only one pressure angle 120 of the four pressure angles 120 is shown.

In Fig. 9 the bearing arrangement 28 is shown with the first axial bearing 90 as a deep groove ball bearing 114 and the second axial bearing 92 as a tapered roller bearing 132. In the case of tapered roller bearings 132, in contrast to the aforementioned bearings, the rolling element 80 is not spherical but rather conical. The truncated cone 134 of the tapered roller bearing 132 does not run on a bearing track 78, but rests on a wider bearing surface 136. The bearing surface 136 is formed on the second bearing inner ring 96 and the second bearing outer ring 106 instead of the bearing track 78. The bearing outer ring 106 and the bearing inner ring 96 are loosely fitted together and must be taken apart for assembly. Because both bearing rings are to be taken apart, there is a greater number of rolling elements 80 between them than in the case of the deep groove ball bearing in FIG Fig. 5 to assemble.

The greater number of rolling elements 80 and the wide bearing surface 136 have the effect that the tapered roller bearing 132 can withstand higher loads in both the radial direction 18 and in the axial direction 16 than a deep groove ball bearing 114 for the same structural size.

In Fig. 10 a bearing arrangement 28 according to the invention is shown in which the two disc springs 100, 102 are each preloaded with a first preload force 138. The first pretensioning force 138 of the plate springs 100, 102 already presses the two bearing inner rings 94, 96 outward or apart in the axial direction 16 when the solid bowl screw centrifuge 10 is at rest. The two bearing inner rings 94, 96 are therefore loaded with this first preload force 138 in the axial direction 16 in the rest state. The first preload force 138 corresponds to half of the axial force 62 of the solid bowl screw centrifuge 10 in the operating state at maximum load in the idle state. In the rest state of the solid bowl screw centrifuge 10, the first axial bearing 90 is loaded with the first preload force 138 in the axial direction 16 opposite the second axial bearing 92.

The embodiment shown here shows the bearing arrangement 28 with the two axial bearings 90, 92 which is loaded with an axial force 62. The axial force corresponds to the preload force 138. As can be clearly seen in the case of the first axial bearing 90, based on the raceway 118 aligned with the radial direction 18, the first axial bearing 90 does not absorb any axial force 62. In the case of the second axial bearing 92, it can be seen from the track 118 inclined to the radial direction 18 that the second axial bearing 92 absorbs the axial force 62.

As in Fig. 11 As can be seen, the bearing arrangement 28 comprises a third axial bearing 140 and a further second elastic means 98 on which the third axial bearing 140 is supported in the axial direction 16. The third axial bearing 140 is connected in the axial direction 16 after the second axial bearing 92 in series with the first and second axial bearings 90, 92. As with the first and second axial bearings 90, 92, the third axial bearing 140 comprises a third bearing outer ring 142 and a third bearing inner ring 144 a non-elastic means 110 arranged. The elastic means 98 is arranged in the axial direction 16 between the second and the third bearing inner ring 96, 144. This The elastic means 98 and the elastic means 98 between the first and second bearing inner rings 94, 96 are provided with a second pretensioning force 146. This second pretensioning force 146 corresponds to a third of the axial force 62 of the solid bowl screw centrifuge 10 in the operating state at maximum load in the idle state. Like the second axial bearing 92, the third axial bearing 140 is not pressed onto the support area 64, but is held in the radial direction 18 by the support area 64. The second and third axial bearings 92, 140 are designed as floating bearings that can move in the axial direction 16.

In this exemplary embodiment, the axial force 62 is distributed from the worm hub 34 to the three axial bearings 90, 92, 140. Due to the distribution of the axial force 62 over three axial bearings 90, 92, 140, the individual axial bearings 90, 92, 140 are dimensioned with a smaller height 66.

In conclusion, it should be noted that all features that are mentioned in the application documents and in particular in the dependent claims, despite the formal reference made to one or more specific claims, should also be given independent protection individually or in any combination.

List of reference symbols

10

Solid bowl screw centrifuge

12th

Centrifuge axis

14th

Centrifuge drum

16

Axial direction

18th

Radial direction

20th

casing

22nd

first drum bearing

24

second drum bearing

26th

Drum cover

28

Bearing arrangement

30th

Thrust bearings

32

slug

34

Worm hub

36

Helix

38

Screw bearings

40

Inlet pipe

42

Inlet room

44

mixed material

46

Separation room

48

difficult phase

50

easy phase

51

Fluid level

52

Pond depth

54

Outlet opening

56

Weir plate

58

Discharge opening

60

Conveying direction

62

Axial force

64

Support area

66

Storage height

68

Wall thickness

70

outer diameter

72

Inside diameter

74

Bearing inner ring

76

Fixing ring

78

Warehouse track

80

Rolling elements

82

Bearing outer ring

84

Fixing ring

86

Ring seal

88

Ring seal

90

first axial bearing

92

second axial bearing

94

first bearing inner ring

96

second bearing inner ring

98

elastic means

100

first disc spring

102

second disc spring

104

first bearing outer ring

106

second bearing outer ring

108

less elastic means

110

non-elastic means

112

Groove

114

Deep groove ball bearings

116

Spindle bearing

118

career

120

Pressure angle

122

Angular contact ball bearings

124

Four point bearings

126

Point of contact

128

first half

130

second half

132

Tapered roller bearings

134

Truncated cone

136

storage area

138

first preload

140

third thrust bearing

142

third bearing outer ring

144

third bearing inner ring

146

second preload

Claims (10)

1. A solid bowl screw centrifuge (10) having a centrifuge axis (12), a screw (32), and having a bearing arrangement (28) of the screw (32) comprising a first axial bearing (90) and a second axial bearing (92), which are provided for receiving an axial force (62) of the screw (32),
   characterized in that an elastic means (98) is provided against which the second axial bearing (92) is supported for supporting the axial force (62) of the screw in the axial direction (16).
2. The solid bowl screw centrifuge according to claim 1,
   characterized in that the elastic means (98) is arranged between the first and the second axial bearing (90, 92).
3. The solid bowl screw centrifuge according to claim 1 or 2,
   characterized in that the first and the second axial bearing (90, 92) each are configured with a bearing inner ring (94, 96) and a bearing outer ring (104, 106), the elastic means (98) is arranged between the two bearing inner rings (94, 96), and a less elastic means (108), in particular a non-elastic means (110) is arranged between the two bearing outer rings (104, 106).
4. The solid bowl screw centrifuge according to claim 1 or 2,
   characterized in that the first and the second axial bearing (90, 92) each are configured with a bearing inner ring (94, 96) and a bearing outer ring (104, 106), the elastic means (98) is arranged between the two bearing outer rings (104, 106), and between the two bearing inner rings (94, 96), a less elastic means (108), in particular a non-elastic means (110) is arranged between the two bearing inner rings (94, 96).
5. The solid bowl screw centrifuge according to any one of claims 1 to 4,
   characterized in that the second axial bearing (92) is configured as a spindle bearing, and the first axial bearing (90) is configured as a grooved ball bearing (114).
6. The solid bowl screw centrifuge according to any one of claims 1 to 4,
   characterized in that the second axial bearing (92) is configured as an angular ball bearing (122), and the first axial bearing (90) is configured as a grooved ball bearing (114).
7. The solid bowl screw centrifuge according to any one of claims 1 to 4,
   characterized in that the second axial bearing (92) is configured as an angular ball bearing (122), and the first axial bearing (90) is configured as a four-point bearing (124).
8. The solid bowl screw centrifuge according to any one of claims 1 to 4,
   characterized in that the second axial bearing (92) is configured as a tapered roller bearing (132), and the first axial bearing (90) is configured as a grooved ball bearing (114).
9. The solid bowl screw centrifuge according to any one of claims 1 to 8,
   characterized in that a third axial bearing (140) is provided for receiving an axial force (62) of the screw (32), and a further elastic means (98) is provided against which the third axial bearing (140) is supported in the axial direction (16).
10. The solid bowl screw centrifuge according to any one of claims 1 to 9,
    characterized in that the elastic means (98), in particular the further elastic means (98) has pretension.

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